Away3D Forum How "AWPRigidBody.applyCentralForce()" affects "AWPRigidBody.front"?

How “AWPRigidBody.applyCentralForce()” affects “AWPRigidBody.front”? Software: Away3D 4.x

erroneous seth, Newbie Posted: 26 October 2011 03:25 PM Total Posts: 28 Hello to everyone, I try to move a Sphere on a Plane. I use the mouse’s “x offset” from the center of the screen to rotate the Sphere. Then, when the user “presses the ctrl button and clicks” a constant force is applied to the Sphere. The code used is the following: `private function onMouseClick(event : MouseEvent) : void { force = sphere.forwardVector; force.negate(); force.scaleBy(BALL_FORCE); if (event.ctrlKey) { sphereRigidBody.applyCentralForce(force); } trace("force.x: " + force.x + ", force.y: " + force.y + ", force.z: " + force.z); }` (BALL_FORCE is a Number declared as “private static const”) And the traces received are: force.x: 0, force.y: 0, force.z: -700 force.x: 0, force.y: 0, force.z: -700 force.x: 0, force.y: -41.85575713419593, force.z: 698.7475192047004 force.x: 0, force.y: 699.308698847882, force.z: 31.10214969551242 force.x: 0, force.y: 698.5301337461049, force.z: 45.339301369218916 force.x: 0, force.y: 694.9358876001116, force.z: 84.0482725904877 As you can see, after 2 or 3 loops the “front” vector changes direction as far as its height (y-axis) is concerned while the “force” applied remains the same (or at least, I think it does). So, I would like to ask how does the “applyCentralForce” method affects the “front” property of an AWPRigidBody? Thank you very much.
John Brookes, Moderator Posted: 26 October 2011 05:27 PM Total Posts: 732 [ # 1 ] The sphere rolls so the forward vector changes.
erroneous seth, Newbie Posted: 28 October 2011 12:58 PM Total Posts: 28 [ # 2 ] Thank you very much for your answer. I thought so, too. As I understand, I will have to manually calculate a “front vector” without taking into account the current rotation of the “mesh”. I will post “source code” and results.
John Brookes, Moderator Posted: 28 October 2011 01:38 PM Total Posts: 732 [ # 3 ] Use torque to roll. This uses Torque impulse and moves a sphere with keys based on where a camera orbiting the origin is looking `var cmP:Vector3D = camera.position.clone(); cmP.normalize(); cmP.scaleBy((sphereRollForce / 60));//60=fps if (keyForward) myRigidBody.applyTorqueImpulse(new Vector3D(cmP.z * -1, 0, cmP.x)); if (keyReverse) myRigidBody.applyTorqueImpulse(new Vector3D(cmP.z, 0, cmP.x * -1)); if (keyLeft) myRigidBody.applyTorqueImpulse(new Vector3D(cmP.x * -1, 0, cmP.z * -1)); if (keyRight) myRigidBody.applyTorqueImpulse(new Vector3D(cmP.x, 0, cmP.z));`
erroneous seth, Newbie Posted: 01 November 2011 03:55 AM Total Posts: 28 [ # 4 ] JohnBrookes, thank you very much for your answer. I found a way to deal with the changing “front vector”. However, my solution still uses the “applyCentralForce” method. I don’t know if it is more suitable than using torque, as you suggest. Below, I explain the solution I came up with. Since, the only thing given is the new force vector’s angle relative to the sphere’s local “z-axis”, the following constitutes the calculation of the new force vector: 1. decomposition of the new force vector to its “x & z” components 2. addition of the two components to produce the new force’s vector The code used: private function updateForce() : void { /* Angle between sphere "z-axis" and new force. / var theta:Number = _forceAngleMathConsts.DEGREES_TO_RADIANS; /* Decompose new force's vector to its "z" and "x" component. / var xFactorLength:Number = Math.sin(theta); var zFactorLength:Number = Math.cos(theta); / Compose the new force from its components. */ _force = new Vector3D(xFactorLength, 0, zFactorLength); _force.negate(); } Thank you for your answers.

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